1. Field of the Invention
The invention relates to a stamp unit having a holder member which is disposed slidably in an axial direction within a skirt member and holds a stamp material at the lower end portion, and a grip member which is disposed on the upper portion of the holder member and moves the holder member downwardly and, more specifically, to a stamp unit which has an ink pack filled with ink within the holder member and opens the ink pack by the grip member and the holder member, and can supply ink to the stamp material, and also to a method for supplying ink to a stamp unit.
2. Description of the Related Art
Heretofore, several types of stamp units have been proposed. To focus on the method for producing a stamp plate used on such a stamp unit, stamp units will be classified into the following two groups. A type of stamp unit, for example, is disclosed in Japanese unexamined Patent Application Publication Nos. HEI-7-149031, HEI-7-257001. Such a type of stamp unit has a grip portion, a stamp portion and a skirt member, the grip portion and the stamp portion are connected so that the stamp portion can be moved in an axial direction within the skirt member. A stamp material is installed covering the lower surface of an ink impregnated body. The stamp material comprises a thermal porous sheet having a porous substrate adhered to a thermoplastic film.
In the case of producing a stamp plate capable of printing characters and the like from the stamp material using such a stamp unit, the stamp unit is set to a stamp producing apparatus having a thermal head, then the thermal porous sheet of the stamp material is perforated according to the desired characters by controlled heating of the thermal head, thereby the stamp plate is produced. After that, when printing characters and the like, if the grip portion is pressed downward under the condition that the stamp unit is disposed on the desired position of the printing sheet, ink impregnated by the ink impregnated body attaches to the printing sheet through holes formed on the thermal porous sheet. Thereby, characters and the like can be printed.
Another type of stamp unit is described in European unexamined Patent-Application Publication No. EP 0 798 114 A2, having a grip portion and a holder portion. The holder portion is connected to the grip portion. A stamp surface producing material is provided on the lower surface of the holder portion.
The stamp surface forming material of such a stamp unit comprises a porous resin layer. The porous resin layer is melted and solidified by being heated. So as to process this stamp surface producing material, the stamp surface is exposed by a heating unit, such as a xenon tube or a laser light source, according to desired characters or image data. Thereby, the part of the stamp surface, which is exposed, that which does not include characters or image data, is melted and solidified. On the other hand, the other part of the stamp surface forming material forming the characters or image data, which has neither melted nor solidified, remains as it is. Thereby, the stamp plate is produced of the stamp surface forming material. When printing characters and the like, the grip portion is pressed downward when the stamp unit is properly positioned. Thereby, ink impregnated in the stamp surface forming material is exuded from nonmelted-solidified portion and adheres to the printing sheet printing the characters and the like.
In the first type of stamp unit, ink is impregnated into the ink impregnated body in advance. If characters cannot be printed because of a lack of ink after repeated printing, the stamp unit is disposed of. In this type, the ink impregnated body can be supplied ink only once because of the difficulty of impregnating ink, after use, into the ink impregnated body.
To easily re-impregnate ink, the ink storing portion for storing ink at the stamp portion must be formed separately. The stamp structure must have a capability to supply ink into the storing portion from outside of the stamp unit. As mentioned above, forming the ink storing portion and the ink supply structure complicate the structure of the stamp portion and the cost increases.
Further, in case of printing characters using the second type of stamp unit, it is necessary that ink be impregnated into the nonmelted-solidified portion of the stamp surface forming material by applying ink from outside on the stamp surface of the stamp surface forming material. Using such a method for spreading and impregnating ink means the process of impregnating ink into the stamp surface forming material must be performed very often. Because such a process is very complicated, printing characters cannot be done efficiently.